Greases thickened with polyurea



United States Patent 3,243,372 GREASES THICKENED WITH POLYUREA John L. Dreher, Berkeley, and Judson E. Goodrich, San

Rafael, Calif, assignors to Chevron Research Company, a corporation of Delaware No Drawing. Filed Mar. 16, 1965, Ser. No. 440,287 16 Claims. (Cl. 252-515) This application is a continuation-in-part of applications Serial Nos. 84,511, filed January 24, 1961; 109,827, filed May 15, 1961, and 210,559, filed July 17, 1962, all now abandoned.

This invention concerns novel greases thickened with p'olyureas. More particularly, this invention concerns novel greases thickened with polyureas of at least 4 urea groups having hydrocarbon terminal end members.

There has been an increasing need for greases which are operable at elevated temperatures, that is, temperatures above 350 F. and preferably temperatures above 400 F. The need is a result of the increasing speed and energy requirements of the jet age. Gears, bearings, and other moving parts are required to operate at greater speed and higher loads than have heretofore been required. This has resulted in ever-increasing temperatures occurring in the area of the moving parts.

For the most part, high temperature grease thickening agents have been fatty acid salts. Illustrative of such thickeners which provide relatively high melting point grease compositions are the lithium soaps of various fatty acids. However, these fatty acid salts catalyze the oxidation of the lubricant. At the higher temperatures of operation, the rapid oxidative degradation of the lubricant increases the frequency with which the old lubricant must be removed and new grease lubricant applied to the moving surface.

Pursuant to this invention, greases having relatively high dropping points are provided which have, in an amount sufficient to provide thickening to a grease, polyureas of the following formula:

wherein x is an integer of from 1 to 3, R and R may be the same or different and are hydrocarbylene of from 2 to 30 carbon atoms (hydrocarbylene is a divalent organic radical composed solely of carbon and hydrogen which may be aliphatic, alicyclic or aromatic or combinations thereof, e.g., alkaryl, aralkyl, etc., having its two free valences on different carbon atoms); R and R" may be the same or different and are hydrocarbyl of from 1 to 30 carbon atoms (hydrocarbyl is a monovalent organic radical composed solely of carbon and hydrogen which may be aliphatic, aromatic, or alicyclic or combinations thereof, e.g., aralkyl, alkaryl, etc.).

The polyureas of the above formula are readily prepared by mixing diisocyanates and diamines with monoisocyanates or monoamines in the proper proportions to form the desired polyurea. The greases thickened with the polyureas are useful at temperatures from about 100 F. to 500 F. and remain unctuous after long use, not becoming hard or brittle. The grease compositions thus formed are extremely resistant to emulsification in water.

The preferred greases are thickened by compositions of the following formula:

wherein x is an integer of from 1 to 3, preferably, 1, R and R are the same or different and are hydrocarbyl of from 5 to 28 carbon atoms, preferably of from 6 to 25 carbon atoms and R and R may be the same or different and will be hydrocarbylene of from 2 to 26 carbon atoms, more usually of from 2 to 18 carbon atoms. It is further preferred that in the tetraureas, the sum of the carbon atoms of R and R is in the range of 10 to 30 and the sum of the carbon atoms of R and R is in the range of 12 to 40.

The monoamine -or monoisocyanate used in the formation of the polyurea will form the terminal end group. As already indicated, these terminal end groups will be of from 1 to 30 carbon atoms, but are preferably of from 5 to 28 carbon atoms and more desirably of from 6 to 25 carbon atoms. As already indicated, the substituent on the nitrogen is a hydrocarbon radical which may be aliphatic, aromatic or alicyclic, may be aliphatically saturated or unsaturated, or may be combinations of the various types of hydrocarbon radicals.

Illustrative of various monoamines are pentylamine, hexylamine, heptylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, eicosylamine, dodecenylamine, hexadecenylamine, octadecenylamine, octadecadienylamine, abietylamine, aniline, toluidine, naphthyla'mine, cumylamine, bornylamine, fenchylamine, tert.-butyl aniline, benzylamine, B-phenethylamine, etc.

Illustrative of monoisocyanates are hexylisocyanate, decylisocyanate, dodecylisocyanate, tetradecylisocyanate, hexadecylisocyanate, phenylisocyanate, cyclohexylisocyanate, tolueneisocyanate, xyleneisocyanate, cumeneisocyanate, abietylisocyanate, cyclooctylisocyanate, etc.

The preferred aromatic terminal end groups are those of from 6 to 12 carbon atoms. The preferred aliphatic terminal end groups are those of from 10 to 20 carbon atoms.

The diamines and diisocyanates which form the internal hydrocarbon bridges between the ureas are, as indicated, of from 2 to 30 carbon atoms, preferably from 2 to 26 carbon atoms and more desirably of from 2 to 18 carbon atoms.

Illustrative of various diamines are ethylenediamine, propanediamine, butanediamine, hexanediamine, dodecanediamine, octanediamine, hexadecanediamine, cyclohexanediamine, cyclooctanediamine, phenylenediamine, toluenediamine, xylenediamine, dianilinemethane, ditoluidinemethane, bisaniline, bistoluidine, etc.

Illustrative of diisocyanates are hexanediisocyanate, decanediisocyanate, octadecanediisocyanate, phenylenediisocyanate, toluenediisocyanate, bis(diphenylisocyanate), methylene bis(phenylisocyanate), etc.

The aromatic hydrocarbylene or bridging groups will generally be of from about 6 to 18 carbon atoms. The aliphatic hydrocarbylene or bridging groups will generally be of from about 2 to 10 carbon atoms.

The polyurea grease thickeners have a polar/nonpolar balance. That is, there will be at least about 6 carbon atoms per urea group and more usually about 8 carbon atoms per urea group, but fewer than 20 carbon atoms per urea group and more usually fewer than 16 carbon atoms per urea group.

The tetraureas used in this invention have the following formula:

0 o R NHL INHR NHiiNHR NHiiNHR NHiiNHR 3 wherein R R R and R are as defined previously.

The greases of this invention are formed with a wide variety of oils of lubricating viscosity. Various base oils include naphthenic base, parafiin base and mixed base mineral lubricating oils; synthetic oils, such as polymers of propylene, butylene, etc., propylene oxide polymers, carboxylic acid esters, e.g., isooctyl azelate, pentaerythritol caproate or dipropylene glycol dipelagonate; silicon esters, such as tetraethyl silicate, hexa-(4-methyl-2-pentoxy)disiloxane, etc.

The greases have the polyureas in the oils of lubricating viscosity in amounts sufficient to thicken the oil to the consistency of grease, that is, in amounts ranging from 5% to 50% by weight, preferably, in amounts from 6 to 25% by weight.

The greases will generally have dropping points in excess of 400 F. and more usually in excess of 450 F.

As indicated when preparing the polyureas, the monoamines or isocyanates are merely brought together with the diisocyanates and diamines in the proper proportion, preferably in the presence of an inert diluent. Usually, the vehicle to be thickened or gelled will be the preferred diluent. It is not necessary that the diluent be a solvent for all the reactants. With a heterogeneous system, efficient stirring helps to insure smooth reaction between the various reactants.

The temperature of the reaction will generally vary from about 20 C. to about 100 C., more usually from about 20 C. to 75 C. The reaction itself is exothermic and by starting at room temperature, elevated temperatures are obtained. However, external heating or cooling may be desirable. The concentration of polyurea in the final product may vary from about 1 to 50 weight percent, depending on the various reactants, the particular product desired, etc.

The following examples are oifered by way of illustration and not by way of limitation.

EXAMPLE 1.-PREPARATION OF TETRAUREA A mixture of 177.8 g. (0.711 mole) of diphenylmethane, 4,4'-diisocyanate and 350 ml. of methylethylketone (MEK) was heated to 150 F. This mixture was blended with 1200 g. of pentaerythritol caproate (Hercoflex 600). To this blend was added an MEK solution of 38.5 g. (0.356-mole) of p-phenylenediamine, 98 g. (0.364 mole) of Armeen 18-D, which is described hereinbelow, and 37.8 g. (0.353 mole) p-toluidine in 350 ml. of hot MEK with agitation. The whole blend was heated to 300 F at which temperature was added 49.7 g. of commercial oxidation inhibitors and 402.3 g. of pentaerythritol caproate. The temperature was increased to 400 F., after which the composition was pan cooled, then milled twice at 4000 p.s.i. The resulting thickened composition was useful as a grease and had an ASTM unworked penetration (P of 237 and a dropping point of 500+ F.

EXAMPLE 2.PREPARATION OF TETRAUREA A solution of 141.5 g. (0.566 mole) of diphenylmethane, 4,4'-diisocyanate in 350 ml. of methylethylketone (MEK) was blended with 1089 g. of diisooctylazelate with agitation. To this blend was added a solution of 56.1 g. (0.283 mole) of methylene dianiline, 152.2 g. (0.566 mole) of Armeen 18-D in 350 ml. of warm MEK. After this blend has been heated to 300 F., there was added 36.8 g. of commercial oxidation inhibitors. The mixture was heated to 400 F., and 364 g. of diisooctylazelate was added. After pan cooling, the resulting thickened composition was milled at 4000 p.s.i., yielding a grease thickened with 19% tetraurea, and having a P of 275 and a dropping point of 500+ F.

A sample of the tetraurea grease thickener of Example 2 hereinabove was isolated by placing 50.34 g. of the grease for Example 2 in a Soxhlet extractor for 72 hours with refluxing MEK. The cup was then dried in vacuo,

and on analysis the extract solid was found to contain the following:

EXAMPLE 3.-PREPARATION OF HEXAUREA A mixture of 10.8 g. (0.10 mole) of metaphenylene diamine, and 30.0 g. (0.10 mole) of a mixture of primary amines having an average molecular weight of 300, was heated at 300 F. until a solution was obtained. This amine solution was added quickly with rapid agitation to a mixture consisting of.4l.7 g. (0.15 mole) of diphenylmethane, 4,4'-diisocyanate and 300 g. of a California parafiinic base oil having a viscosity of 500 SSU at F. The resulting mixture was stirred in a high speed Waring Blendor for 15 minutes, then heated in an oven at 350 F. for 3 hours, with an occasional mixing by hand. The mixture was cooled to ambient temperatures, then milled through an extrusion-type mill at 5600 p.s.i. After the addition of 75 g. of the same oil described hereinabove, the thickened grease-type composition was milled twice at 5600 p.s.i.

The resulting grease, which contained 15.6% of the hexaurea, had an ASTM worked penetration (P of 294, and an ASTM dropping point of 473 F.

EXAMPLE 4.-PREPARATION OF OCTAUREA A mixture of 16.2 g. (0.15 mole) of metaphenylenediamine and 300 g. (0.10 mole) of the same amine described in Example 3 hereinabove, was heated at 300 F. until solution occurred. This hot amine solution was added quickly with violent agitation to a blend consisting of 55.6 g. (0.20 mole) of diphenylmethane, 4,4-diiso cyanate and 372 g. of a California paraflin base oil having a viscosity of 500 SSU at 100 F. The resulting blend was stirred at high speed for 30 minutes, then heated in an oven at 350 F. for 3 hours, with a mixing by hand every 30 minutes. The grease was cooled to ambient temperature, than milled twice through an extrusion-type mill at 5600 p.s.i.

The finished grease, which contained 19.9% of the octaurea, had an ASTM worked penetration (P of 303,

A mixture of 3.6 g. of ethylenediamine, 30 g. of Armeen T, and 7 g. of an antioxidant was heated at F. for 10 minutes, forming a homogeneous solution. This solution was added quickly to a lubricating oil blend consisting of 223 g. of a California base oil having a viscosity of 480 SSU at 100 F., and 17.4 g. of an isocyanate (an 80/20 mixture of 2,4-toluenediisocyanate and 2,6-toluenediisocyanate) with vigorous agitation in a Waring Blendor. A gel formed immediately. The resulting grease was removed from the blender, hand mixed, and milled at 8000 p.s.i.

The final grease which contained 12.5% thickening 7 agent, had an ASTM worked penetration (P of 290 and an ASTM dropping point of 505 F.

The following table illustrates a number of tetraureas prepared as described in the prior examples. The tetraureas were formed in a variety of oils of lubricating viscosity with varying chemical nature. The ASTM Unworked Penetration (P the ASTM Worked Penetration after 60 strokes in the ASTM worker (P and in many instances, the ASTM Dropping Point in degrees F. are reported.

1 Armeen T is principally an octadecenyl amine sold by the Armour Company, Chicago, Ill.

Table I Tetraurea Characteristics Grease Composition Grease Properties Ex. No. R De- R De- R De- Base Thickener 1 Dropping Diisocyrived rived rived Oil (Wt. Per- P P Point,

anate From From-- Fromcent) A (1) (3) (6) H 17. 5 216 A 1) (3) (6) I-'[ 17.4 237 A (1) (1) (7) J 20. 0 189 A (1) (1) (7) H 16.0 220 B (1) (1) (7) H 15. 8 198 C (1) (l) (7) H 18. 0 208 D (1) (1) (7) H 18. 0 227 E (1) (1) (7) H 18. 0 220 A (1) (3) (7) K 15. 4 254 A (1) (3) (7) K 20. 5 263 A (1) (1) (7) K 19. 0 216 A (2) (2) (7) L 20. 0 218 A (2) (2) (7) M 21. 0 214 A (2) (2) (7) N 1 28. 5 197 A (2) (2) (7) H R 18.8 246 A (4) (4) (7) H 16. 0 252 A (1) (1) (7) O 22. 7 265 1 In addition to the thickener, these greases contained from 1.4% to 2.1% by weight of an oxidation inhibitor 1 No antioxidants were used.

It is evident from the above table, that excellent greases are obtained having low penetrations and high dropping points.

The diisocyanates used in the preparation of the polyureas of Table I are described as follows:

A diphenylrnethane 4,4'-diisocyanate; B 3,3'-dimethyldiphenylmethane 4,4'-diisocyanate, C 3,3'-bitolylene 4,4-diisocyanate; D m-xylylene diisocyanate; E 2,4-, 2,6-lto luenediisocyanate (80/20).

The monoamines from which the R and R" radicals were derived are described as follows:

(1) Octadecylamine sold as Armeen 18D by the Armour Company, Chicago, Illinois;

' (2) A mixture of monoamines sold as Armeen HT by the Armour Company, Chicago, Illinois, containing hexadecylamine, 70% octadecylamine and 5% octadecenylarnine;

(3) p-Toluidine; (4) Rosin Amine (abietyl derived amine sold by Hercu- The following table illustrates three greases prepared according to the prior examples wherein sodium metaborate or sodium metaborate and molybdenum disulfide are incorporated in the grease. The sodium metaborate is an extreme pressure agent, while the molybdenum disulfide provides dry lubricating properties. The ureas formed were tetraureas and the data demonstrate that they are compatible with and operative with the alkali les Chemical Company; metal metaborates as well as molybdenum disulfide.

Table II Grease Composition Grease Properties R R" R Sodium Met- MoS Diisocyaborate Octa- Wt. Peranate Base Wt. Percent 2 hydrate cent Dropping Derived From- Oil Thiekener Wt. Percent Po P Point, F.

23 E 5 3 9 15 1 240 300 484 24 E 5 3 8 Q/K 14 2.2 238 300 443 25 E 5 3 8 Q/K 13 1. 4 5 236 288 450 1 About 2 parts of Q per 5 parts of K. 1 Included in this composition were from 1.4 to 2.1 weight percent of commercial antioxidants and dyes.

(5) Tall oil fatty amine; M.W.=286; N: 4.89%;

Base oil H was pentaerythritol tetracaporate;

Base oil J was a California paraffinic base petroleum oil having a viscosity of 480 SSU at 100 F.;

Base oil K was diisooctylazelate;

In order to demonstrate the effectiveness of the greases prepared using the polyureas, the following tests were carried out.

The bearing life for a particular grease composition was determined by the following test procedure which is known as the Navy High Speed Bearing Test as described in Federal Test Method 331.1. In this test, a ball hearing was operated at 10,000 r.p.m. continuously for approximately 22 hours at the temperature noted in Table III. The apparatus was then cooled to room temperature during a period of 2 hours. This procedure of operating at 10,000 r.p.rn. at the noted temperature and cooling was repeated until there was hearing failure. The bearing life is the number of hours to bearing failure.

7 8 The thickeners were tetraureas, prepared as previously Table V described. The various materials used are described heremafter. Diisocyanate/ Percent The base oils are identified as the same base 0115 used Dwmme Ratio c e er in Table I hereinabove.

In thickener A, the R and R" were derived from egg octadecylamine identified hereinabove as Armeen 18D; 1111: 0 1 1 the diamine was methylene dianiline; and the diisocyanate Was diphenylmethane 4,4'-diisocyanate. (a) Octmmg Thickener B was as follows: the R and R" were de- 10 rived from the octadecylamine identified hereinaibove as Armeen HT, the diamine was methylene dianiline, and As will be evident to those skilled in the art, various the diisocyanate was diphenylmethane 4,4' -diisocyanate. modifications on this invention can be made or followed, Thickener C was prepared as follows; the R a d R" in the light of the foregoing disclosure and discussion, radicals were derived from the octadecylamine described 5 without departing from the spirit or scope of the (11S- hereinabove as Armeen 18D, the diamine was methylene closure or from the scope of the following claims. dianiline, and the diisocyanate was m-Xylylene diisocya- We claim: nate. 1. A grease composition comprising an oil of lubr1cat- Table III Grease Properties Oxidation Thickneer Base Oil Inhibitor Bearing Life (wt. percent) (wt. percent) P P60 Temp., H0urs* A (20.0 J 2,0 189 289 350 216 A(16. 0) H 1.6 220 291 350 424 B (18.0) H 1.6 227 300 350 710 o (28.5) N 0.0 197 296 450 12s A 22.7 o 2.0 265 305 450 117 *Geometric Mean of 2 tests.

Table IV below resents f rth r d ta n th physical ing viscosity and in an amount suflicient to thicken said characteriistics of grease compositions thickened with oil to the consistency of a g a p y f t f tetraureas. :mula

In all instances, the diisocyanate was an 80/20 blend O O of 2,4 toluencdiisocyanate and 2,6-tolucnediisocyanate. ll ll 1L The monoamines from which the R and 'R" radicals 40 R GNH R NHONH R R NHCNH R werefienved are s 'g g wherein x is a number having a value from 1 to 3, R (I) Armeen HT as escnbed erema and R" are hydrocarbon radicals containing from 1 to (2) Armeen T as described hereinabove.

. 30 t d R h d d The R radicals were derived from diammes described carbon a Oms R an are y rocarbon Ia lcals containing from 2 to 30 carbon atoms, wherein the ratio as follows: of carbon atoms to the number of urea rou s is at (3) Meta-xylenediamine; least g p -p ly l 2. A grease composition according to claim 1 where- (5) Ethyl n d in said polyurea is present in an amount of from 5 to The base oil was a California base petroleum oil havpercent by i ht f said total composition. mg a viscosity of 80 SSU at 100 50 3. A grease composition according to claim 1 wherein Table IV Urea Characteristics Grease Properties R, R R (Thiekenert D W eroen Derived Derived Derived p P P Po i tf From- From- From- (1) (1) a) 13. 3 240 297 500 2 2 E4 10. s 216 286 500i 2) 2 5) 12. 5 245 290 500+ I In addition to the thickener, the greases contained from 1.4% to 2.1% by weight, of an oxication inhibitor.

Table V hercinbelow presents additional data showing said polyurea is present in an amount of from 6 to 25 the eifectiveness of the greases of this invention. As prepercent by weight of said total composition. pared, a polyurea was used in that amount sufiicient to 4. A grease composition comprising an oil of lubricatproduce a grease having an ASTM worked penetration ing viscosity and in an amount sufiicient to thicken said (P of approximately 290. The data shows the diisooil to the consistency of a grease, a polyurea of the forcyanate/diamine mole ratio. mula The diisocyanate which was used was an 80/20 mixture (fl) H (i? of 2,4-tolyldiisocyanate and 2,6-tolyldiisocyanate. H, I I

The diamine was ethylenediamine, and the mOnO- NH CNH R NHCNH R /X CNH R NHCNLPR,

amine was A-rmeen T defined hereinabove. wherein x is a number having a value of from 1 to 3, R

9 and R" are hydrocarbon radicals of from 5 to 28 carbon atoms, and R and R are hydrocarbon radicals of from 2 to 26 carbon atoms, wherein the ratio of carbon atoms to the number of urea groups is at least about 6:1.

5. A grease composition comprising an oil of lubricating viscosity and in an amount sufficient to thicken said oil to the consistency of a grease, a polyurea of the formula wherein R and R are hydrocarbyl of from 5 to 28 carbon atoms, and R and R are hydrocarbylene of from 2 to 26 carbon atoms, wherein the ratio of carbon atoms to the number of urea groups is at least about 6: 1.

6. A grease composition according to claim 5 wherein R and R are from 6 to 25 carbon atoms and R and R are from 2 to 18 carbon atoms.

7. A grease composition according to claim 5 wherein R and RF are aliphatic of from 10 to 20 carbon atoms.

8. A grease composition according to claim 5 wherein R is an aliphatic radical of from 10 to 20 carbon atoms and R is an aryl radical of from 6 to 12 carbon atoms.

9. A grease composition according to claim 5 wherein the sum of the carbon atoms of R and R is in the range of 10 to 30.

10. A grease composition according to claim 5 wherein the sum of the carbon atoms of R and R is in the range of 10 to 30 and the sum of the carbon atoms of all of the R and R groups is in the range of 12 to 40.

11. A grease composition comprising an oil of lubricating viscosity and in an amount suflicient to thicken said 10 oil to the consistency of a grease, a polyurea of the formula o R NHJiNHR NH NHR' NH NHR NH NHR wherein R and R are hydrocarbyl of from 5 to 28 carbon atoms, R is an aliphatic hydrocarbon divalent radical of from 2 to 18 carbon atoms and R is an aromatic hydrocarbon divalent radical of from 6 to 18 carbon atoms, wherein the ratio of carbon atoms to the number of urea groups is at least about 6: 1.

12. A grease composition according to claim 11 wherein R is tolylene.

13. A grease composition according to claim 11 Wherein R is of the formula References Cited by the Examiner UNITED STATES PATENTS 2,832,739 4/1958 Swakon 25251.5

DANIEL E. WYMAN, Primary Examiner.

I. VAUGHN Assistant Examiner. 

1. A GREASE COMPOSITION COMPRISING AN OIL OF LUBRICATING VISCOSITY AND IN AN AMOUNT SUFFICIENT TO THICKEN SAID OIL TO THE CONSISTENCY OF A GREASE, A POLYUREA OF THE FORMULA 